Effects of chicken manure application on bioavailability of Cd, Pb and As in soil and vegetable growth

A field experiment was conducted to investigate effects of chicken manure application on bioavailability of heavy metals Cd, Pb and As in soil and vegetable growth. On the treatment sites Malabar spinach (Gynura cusimbua), eggplant (Solanum melongena) and no vegetable were planted respectively with different amounts of chicken manure fertilization. All the responses of total heavy metal contents (Cd, Pb and As) and their availability in soil, heavy metal uptake by vegetables and their growth were measured. The results showed that contents of Cd and As were high in chicken manure, which increased or kept the total heavy metal contents in soil. Also, the heavy metal Pb with relatively low contents in chicken manure could accumulate in soil after planting vegetables. With no chicken manure fertilizer, the total content of As in soil decreased significantly after planting vegetables. When the chicken manure amount was 12 000 kg/hm2, the Cd bioavailability in the soil with vegetable planting increased most than other treatments. And when the chicken manure amounts were 8 000, 12 000 and 16 000 kg/hm2, the As bioavailability in soil with three different planting treatments all decreased. The Cd and Pb contents in Malabar spinach first decreased and then increased, while As content displayed contrary tendency. Besides, the yields of Malabar spinach first increased and then decreased with the chicken manure fertilizer increasing. But the fertilizer amount had no significant effect on the yield and biomass of eggplant.